The extensive role of the TGFb/Smad pathway in physiology and disease raises the need for a better understanding of the functions and regulation of this pathway. CA34610 has been our main venue for delineating the TGFb/Smad pathway. The first decade of work under CA34610 set the bases for elucidating the basic components of the TGFb/Smad pathway, which was accomplished during the second decade. In its third decade, CA34610 is devoted to elucidating the integration of the TGFb/Smad pathway in the signaling networks of the cell and its corruption in cancer. Our current Specific Aims will address this general problem in several complementary ways by focusing on Smad proteins and their partners as nodes for signal integration. To this end, we will investigate how diverse signals (RAS, GSK3, BMP) are integrated through phosphorylation of the Smad linker region and how these events control Smad function and degradation (Aim I). Having identified FoxO forkhead factors as key partners of Smads in the mediation of TGFb cytostatic responses, we will determine the role of multiple FoxO regulatory inputs (PI3K, IKK, SIRT1 and others) as modifiers of the cellular response to TGFb (Aim II). Further, we will investigate the biological significance of diverse cellular functions (morphogenesis, metastasis, negative feedback) that are controlled by the FoxO-Smad complex along with cell cycle arrest (Aim III). Beyond this, we will seek to identify novel central components and regulators of the TGFb/Smad pathway, including TIF1g as an alternative to Smad4 in TGFb signaling and the identity of Smad phosphatases, through the use of novel chemical, biochemical and functional proteomics approaches (Aim IV). Through this proposed work, we wish to furnish the field with a better understanding of the role of the TGFb/Smad pathway in physiology and a better ability to manage this pathway in tumor progression, metastasis and other disorders.